Sediments are small pieces of rock that are moved and deposited by water, wind, glaciers, and gravity. When sediments become glued together, they form sedimentary rocks. The formation of sedimentary rocks begins when weathering and erosion produce sediments. Sedimentary rocks form by weathering and erosion. The weathering and erosion break off sediments from different rocks to form sedimentary rocks.
Weathering:Weathering produces sediments. The sediments range in size from huge boulders to microscopic particles. Chemical weathering occurs when the minerals in a rock are dissolved or otherwise chemically changed. While the less-stable minerals are chemically broken down, the more-resistant grains are broken off of the rock as smaller grains. Erosion:Erosion is the removal and transport of sediment. Wind, moving water, gravity, and glaciers transport the sediments. After the rock fragments and sediments have been weathered out of the rock, they are usually transported to new locations through the process of erosion.
Desposition:
Classification
Texture/grain size
Composition
Rock Name
Clastic
coarse(>2mm)
medium(1/16mm to 2mm)
fine(1/256 mm-1/16 mm)
very fine(<1/256 mm)
fragments of any rock type -- quartz, chert, and quartzite common ----
quartz and rock fragments
quartz, potassium feldspar and rock fragments----
quartz and clay----
quartz and clay
conglomerate breccia
sandstone arkose
siltstone----
shale
Biochemical
microcrystalline with conchoidal fracture
abundant fossils in micrite matrix----
oolites (small spheres of calcium carbonate)----
shells and shell fragments loosely cemented----
microscopic shells and clay----
Sedimentary Rocks
How are sedimentary rocks formed?
Sediments are small pieces of rock that are moved and deposited by water, wind, glaciers, and gravity. When sediments become glued together, they form sedimentary rocks. The formation of sedimentary rocks begins when weathering and erosion produce sediments. Sedimentary rocks form by weathering and erosion. The weathering and erosion break off sediments from different rocks to form sedimentary rocks.
Weathering:Weathering produces sediments. The sediments range in size from huge boulders to microscopic particles. Chemical weathering occurs when the minerals in a rock are dissolved or otherwise chemically changed. While the less-stable minerals are chemically broken down, the more-resistant grains are broken off of the rock as smaller grains.
Erosion:Erosion is the removal and transport of sediment. Wind, moving water, gravity, and glaciers transport the sediments. After the rock fragments and sediments have been weathered out of the rock, they are usually transported to new locations through the process of erosion.
Desposition:
medium(1/16mm to 2mm)
fine(1/256 mm-1/16 mm)
very fine(<1/256 mm)
quartz and rock fragments
quartz, potassium feldspar and rock fragments----
quartz and clay----
quartz and clay
sandstone arkose
siltstone----
shale
abundant fossils in micrite matrix----
oolites (small spheres of calcium carbonate)----
shells and shell fragments loosely cemented----
microscopic shells and clay----
variously sized fragments
----
calcite (CaCO3)
calcite (CaCO3)
calcite (CaCO3
----
calcite (CaCO3)----
----
highly altered plant remains, some plant fossils
fossiliferous limestone
oolitic limestone
coquina
chalk
coal
fine to coarsely crystalline
very finely crystalline
fine to coarsely crystalline
fine to coarsely crystalline
dolomite (Ca,Mg)CO3 (will effervesce if powered)
quarts(SiO2)----
light colored----
dark colored----
gypsum (CaSO4 x 2H2O)----
halite (NaCI)
dolostone
chert
flint----
rock gypsum----
rock salt